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Subject[RFC PATCH] x86: Add a sanity test of x86 decoder
Date
Add a sanity test of x86 insn decoder against the random
input. This test is also able to reproduce the bug by
passing random-seed and iteration-number, or by passing
input while which has invalid byte code.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
---

arch/x86/tools/Makefile | 10 +-
arch/x86/tools/insn_sanity.c | 253 ++++++++++++++++++++++++++++++++++++++++++
2 files changed, 262 insertions(+), 1 deletions(-)
create mode 100644 arch/x86/tools/insn_sanity.c

diff --git a/arch/x86/tools/Makefile b/arch/x86/tools/Makefile
index f820826..3255c3d 100644
--- a/arch/x86/tools/Makefile
+++ b/arch/x86/tools/Makefile
@@ -18,14 +18,22 @@ chkobjdump = $(srctree)/arch/x86/tools/chkobjdump.awk
quiet_cmd_posttest = TEST $@
cmd_posttest = ($(OBJDUMP) -v | $(AWK) -f $(chkobjdump)) || $(OBJDUMP) -d -j .text $(objtree)/vmlinux | $(AWK) -f $(distill_awk) | $(obj)/test_get_len $(posttest_64bit) $(posttest_verbose)

-posttest: $(obj)/test_get_len vmlinux
+quiet_cmd_sanitytest = TEST $@
+ cmd_sanitytest = $(obj)/insn_sanity $(posttest_64bit) -m 1000000
+
+posttest: $(obj)/test_get_len vmlinux $(obj)/insn_sanity
$(call cmd,posttest)
+ $(call cmd,sanitytest)

hostprogs-y := test_get_len
+hostprogs-y := insn_sanity

# -I needed for generated C source and C source which in the kernel tree.
HOSTCFLAGS_test_get_len.o := -Wall -I$(objtree)/arch/x86/lib/ -I$(srctree)/arch/x86/include/ -I$(srctree)/arch/x86/lib/ -I$(srctree)/include/

+HOSTCFLAGS_insn_sanity.o := -Wall -I$(objtree)/arch/x86/lib/ -I$(srctree)/arch/x86/include/ -I$(srctree)/arch/x86/lib/ -I$(srctree)/include/
+
# Dependencies are also needed.
$(obj)/test_get_len.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/inat.c $(srctree)/arch/x86/include/asm/inat_types.h $(srctree)/arch/x86/include/asm/inat.h $(srctree)/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c

+$(obj)/insn_sanity.o: $(srctree)/arch/x86/lib/insn.c $(srctree)/arch/x86/lib/inat.c $(srctree)/arch/x86/include/asm/inat_types.h $(srctree)/arch/x86/include/asm/inat.h $(srctree)/arch/x86/include/asm/insn.h $(objtree)/arch/x86/lib/inat-tables.c
diff --git a/arch/x86/tools/insn_sanity.c b/arch/x86/tools/insn_sanity.c
new file mode 100644
index 0000000..9ba74fe
--- /dev/null
+++ b/arch/x86/tools/insn_sanity.c
@@ -0,0 +1,253 @@
+/*
+ * x86 decoder sanity test - based on test_get_insn.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ *
+ * Copyright (C) IBM Corporation, 2009
+ * Copyright (C) Hitachi, Ltd., 2011
+ */
+
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#define unlikely(cond) (cond)
+
+#include <asm/insn.h>
+#include <inat.c>
+#include <insn.c>
+
+/*
+ * Test of instruction analysis against tampering.
+ * Feed random binary to instruction decoder and ensure not to
+ * access out-of-instruction-buffer.
+ */
+
+#define DEFAULT_MAX_ITER 10000
+#define INSN_NOP 0x90
+
+static const char *prog;
+static int verbose;
+static int x86_64;
+static unsigned int seed;
+static unsigned long nr_iter;
+static unsigned long max_iter = DEFAULT_MAX_ITER;
+static char insn_buf[MAX_INSN_SIZE * 2];
+static FILE *input_file;
+
+static void usage(const char *err)
+{
+ if (err)
+ fprintf(stderr, "Error: %s\n\n", err);
+ fprintf(stderr, "Usage: %s [-y|-n|-v] [-s seed[,no]] [-m max] [-i input]\n", prog);
+ fprintf(stderr, "\t-y 64bit mode\n");
+ fprintf(stderr, "\t-n 32bit mode\n");
+ fprintf(stderr, "\t-v Verbose mode\n");
+ fprintf(stderr, "\t-s Give a random seed (and iter number)\n");
+ fprintf(stderr, "\t-m Give a max iteration number\n");
+ fprintf(stderr, "\t-i Give an input file with decoded binary\n");
+ exit(1);
+}
+
+static void dump_field(FILE *fp, const char *name, const char *indent,
+ struct insn_field *field)
+{
+ fprintf(fp, "%s.%s = {\n", indent, name);
+ fprintf(fp, "%s\t.value = %d, bytes[] = {%x, %x, %x, %x},\n",
+ indent, field->value, field->bytes[0], field->bytes[1],
+ field->bytes[2], field->bytes[3]);
+ fprintf(fp, "%s\t.got = %d, .nbytes = %d},\n", indent,
+ field->got, field->nbytes);
+}
+
+static void dump_insn(FILE *fp, struct insn *insn)
+{
+ fprintf(fp, "Instruction = {\n");
+ dump_field(fp, "prefixes", "\t", &insn->prefixes);
+ dump_field(fp, "rex_prefix", "\t", &insn->rex_prefix);
+ dump_field(fp, "vex_prefix", "\t", &insn->vex_prefix);
+ dump_field(fp, "opcode", "\t", &insn->opcode);
+ dump_field(fp, "modrm", "\t", &insn->modrm);
+ dump_field(fp, "sib", "\t", &insn->sib);
+ dump_field(fp, "displacement", "\t", &insn->displacement);
+ dump_field(fp, "immediate1", "\t", &insn->immediate1);
+ dump_field(fp, "immediate2", "\t", &insn->immediate2);
+ fprintf(fp, "\t.attr = %x, .opnd_bytes = %d, .addr_bytes = %d,\n",
+ insn->attr, insn->opnd_bytes, insn->addr_bytes);
+ fprintf(fp, "\t.length = %d, .x86_64 = %d, .kaddr = %p}\n",
+ insn->length, insn->x86_64, insn->kaddr);
+}
+
+static void dump_stream(FILE *fp, const char *msg, struct insn *insn)
+{
+ int i;
+ fprintf(fp, "%s:\n code:", msg);
+ for (i = 0; i < MAX_INSN_SIZE; i++)
+ fprintf(fp, " %02x", insn_buf[i]);
+ fprintf(fp, "\n");
+ dump_insn(stderr, insn);
+ fprintf(fp, "\n This can be reproduced with \"-s 0x%x,%lu\" option\n",
+ seed, nr_iter);
+}
+
+static void get_seed(void)
+{
+ int fd;
+
+ fd = open("/dev/urandom", O_RDONLY);
+ if (!fd)
+ usage("Failed to open /dev/urandom");
+ if (read(fd, &seed, sizeof(seed)) != sizeof(seed))
+ usage("Failed to read /dev/urandom");
+ close(fd);
+}
+
+static int get_next_insn(void)
+{
+ char buf[256] = "", *tmp;
+ int i;
+
+ tmp = fgets(buf, 256, input_file);
+ if (tmp == NULL || feof(input_file))
+ return 0;
+
+ for (i = 0; i < MAX_INSN_SIZE; i++) {
+ ((unsigned char *)insn_buf)[i] = (unsigned char)strtoul(tmp, &tmp, 16);
+ if (*tmp != ' ')
+ break;
+ }
+ return ++nr_iter;
+}
+
+/* generate a random instruction binary */
+static int generate_random_insn(void)
+{
+ int i;
+ if (nr_iter >= max_iter)
+ return 0;
+
+ if (input_file)
+ return get_next_insn();
+
+ /* Fills buffer with random binary up to MAX_INSN_SIZE */
+ if (nr_iter == 0)
+ srand(seed);
+ for (i = 0; i < MAX_INSN_SIZE; i += 2)
+ *(unsigned short *)(&insn_buf[i]) = random() & 0xffff;
+ return ++nr_iter;
+}
+
+static void init_test(int argc, char **argv)
+{
+ int c;
+ char *tmp = NULL;
+ unsigned long iter = 0;
+ int set_seed = 0;
+
+ prog = argv[0];
+ while ((c = getopt(argc, argv, "ynvs:m:i:")) != -1) {
+ switch (c) {
+ case 'y':
+ x86_64 = 1;
+ break;
+ case 'n':
+ x86_64 = 0;
+ break;
+ case 'v':
+ verbose = 1;
+ break;
+ case 'i':
+ if (strcmp("-", optarg) == 0)
+ input_file = stdin;
+ else
+ input_file = fopen(optarg, "r");
+ if (!input_file)
+ usage("Failed to open input file");
+ break;
+ case 's':
+ seed = (unsigned int)strtoul(optarg, &tmp, 0);
+ if (*tmp == ',') {
+ optarg = tmp + 1;
+ iter = strtoul(optarg, &tmp, 0);
+ }
+ if (*tmp != '\0' || tmp == optarg)
+ usage("Failed to parse seed");
+ set_seed = 1;
+ break;
+ case 'm':
+ max_iter = strtoul(optarg, &tmp, 0);
+ if (*tmp != '\0' || tmp == optarg)
+ usage("Failed to parse max_iter");
+ break;
+ default:
+ usage(NULL);
+ }
+ }
+
+ if (max_iter < iter)
+ usage("Max iteration number must be bigger than iter-num");
+
+ if (!set_seed && !input_file) /* Don't get a seed */
+ get_seed();
+ if (set_seed && input_file)
+ usage("Don't use input file (-i) with random seed (-s)");
+
+ /* Prepare stop bytes with NOPs */
+ memset(insn_buf + MAX_INSN_SIZE, INSN_NOP, MAX_INSN_SIZE);
+ /* Skip first nth states */
+ for (; iter > 0; iter--)
+ if (!generate_random_insn())
+ usage("Failed to generate random insns\n");
+}
+
+#define insn_complete(insn) \
+ (insn.opcode.got && insn.modrm.got && insn.sib.got && \
+ insn.displacement.got && insn.immediate.got)
+
+int main(int argc, char **argv)
+{
+ struct insn insn;
+ int insns = 0;
+ int warnings = 0;
+
+ init_test(argc, argv);
+
+ while (generate_random_insn()) {
+ /* Decode an instruction */
+ insn_init(&insn, insn_buf, x86_64);
+ insn_get_length(&insn);
+
+ if (verbose && !insn_complete(insn))
+ dump_stream(stdout, "Undecodable input", &insn);
+
+ if (insn.next_byte <= insn.kaddr ||
+ insn.kaddr + MAX_INSN_SIZE < insn.next_byte) {
+ /* Access out-of-range memory */
+ dump_stream(stdout, "Find access violation", &insn);
+ warnings++;
+ }
+ insns++;
+ }
+ if (warnings)
+ fprintf(stdout, "Warning: decoded and checked %d insns with %d warnings (seed:0x%x)\n", insns, warnings, seed);
+ else
+ fprintf(stdout, "Succeed: decoded and checked %d insns (seed:0x%x)\n", insns, seed);
+ return 0;
+}


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